Shazam

Shazam has many definitions but for mobile users it is an innovative music identification service - although its actually been around since 2002. The service's elegance is in its simplicity, dial 2580 (numbers down the middle of your mobile), hold you phone up to the music, and after around 20 sec the call will end and shortly afterwards you get a message identifying the track.

There are also iPhone/Android/Nokia apps so have a look here for a version for your phone, many have a free trial period. (BTW the apps work internationally.)

Interestingly the technology behind Shazam has also been deployed to audit Radio station air play of tracks. It provides a list of what was actually playing to audit against what was subbmitted for rights payments.